I installed the PL690 on my F658. I think it is not as solid as it should be. It shakes easily.When you are taking a curve and lean the bike, if the surface is a little rough, it shakes a lot. If vibration of the bike matches the resonance frequency of the system, depending on the sizes of the cases, weight etc., you don't feel the rear and anymore. Besides you have to have the top case mount as well to install the side bars. They did not have to design it that way but I guess it is a way of guaranteeing higher sale rates . I am looking into modifying the connection to reduce the shaking. If I cannot, I will be getting rid of them.